1. Field
This disclosure relates to wireless connectivity, especially to establishing connectivity without placing either device in discoverability mode.
2. Related Arts
Various wireless technologies enable inter-connectivity among two or more devices. Such technologies include NFC, WiFi Direct, Bluetooth, etc. Near Field Communication (NFC) is a set of standards for smartphones and similar devices to establish radio communication with each other by touching them together or bringing them into close proximity, usually no more than a few centimeters. Wi-Fi Direct is a standard that allows WiFi devices to connect to each other directly without the need for a wireless access point. The Bluetooth wireless technology standard enables devices to communicate seamlessly when situated in close proximity. What these technologies have in common is the ability of two devices to connect to each other directly using the proper protocol. The protocols generally follow three steps to establish a connection: inquiring device sends a request to target device, target device answers with proper information, inquiring device attempts to connect using the received information.
The following provides a more specific discussion relating to Bluetooth, but as can be appreciated, the discussions provided herein are applicable to other wireless connectivity protocols and technologies. Bluetooth uses a radio technology called frequency-hopping spread spectrum, which chops up the data being sent and transmits chunks of it on up to 79 bands (1 MHz each; centered from 2402 to 2480 MHz) in the range 2,400-2,483.5 MHz (allowing for guard bands). This range is in the globally unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency band. It usually performs 800 hops per second, with AFH enabled.
Bluetooth is a packet-based protocol with a master-slave structure. One master may communicate with up to 7 slaves in a piconet (an ad-hoc computer network using Bluetooth technology), wherein all of the connected devices share the master's clock. Packet exchange is based on the basic clock, which ticks at 312.5 μs intervals. Two clock ticks make up a slot of 625 μs and two slots make up a slot pair of 1250 μs. In the simple case of single-slot packets the master transmits in even slots and receives in odd slots, while the slave receives in even slots and transmits in odd slots. Packets may be 1, 3 or 5 slots long, but in all cases the master transmission will begin in even slots and the slave in odd slots.
The devices connected in a piconet can switch roles, by agreement, and the slave can become the master (for example, a headset initiating a connection to a phone will necessarily begin as master, as initiator of the connection; but may subsequently prefer to be slave). The Bluetooth Core Specification provides for the connection of two or more piconets to form a scatternet, in which certain devices simultaneously play the master role in one piconet and the slave role in another.
To use Bluetooth wireless technology, a device has to be able to interpret certain Bluetooth profiles, which are definitions of possible applications and specify general behaviors that Bluetooth enabled devices use to communicate with other Bluetooth devices. This is also applicable to the other pairing technologies, such as the NFC and WiFi Direct. These profiles include settings to parametrize and to control the communication from start. In order to establish a connection, a Bluetooth device has to operate in a discovery mode. Any Bluetooth device in discoverable mode will transmit the following information on demand: device name, device class, list of services, and technical information (for example: device features, manufacturer, Bluetooth specification used, clock offset). Any device may perform an inquiry to find other devices to connect to, and any device can be configured to respond to such inquiries. However, in general, establishing pairing between two devices requires user intervention. For example, the user needs to place at least one of the devices in discoverable mode and may also be required to enter a security code. With the proliferation of Bluetooth enabled devices, it is many times difficult for users to figure out how to place a device in discovery mode and how to enter the security code.
Tethering is an even more user unfriendly connection procedure and requires significant user involvement and knowledge, such that it generally remains within the realm of a “geek feature,” utilized mainly by tech savvy users. Tethering is mostly used to connect a computer to a cellphone in order to gain access to the Internet, when WiFi or other Internet connection is not available. In addition to requiring user involvement in establishing tethering, various carriers and phone manufacturers place barriers to tethering, leading to various by-pass “creativity,” such as rooting Android devices or jailbreaking iOS devices and installing a tethering application on the device.
In view of the above, a need exists for simplified inter-device connectivity, requiring minimal or no user intervention and/or input. Also, there is clear demand to enabling the use of a phone as an Internet gateway when no direct connection is available. Such a connection should be made available to the most novices of cellphone users, such that it can be widely used.